Pearl-bordered fritillary (Boloria euphrosyne)
|Size||Wingspan: 3.8 - 4.6 cm (1)|
Listed on Schedule 5 of the Wildlife and Countryside Act, 1981 with respect to sale (2).
The pearl-bordered fritillary is pale orange brown in colour with black spots. The underside is paler with reddish brown hindwings featuring pearly silver spots. Both sexes are similar in appearance. The caterpillar is about 2.5 centimetres in length, and has a black body with black, yellow or white spines along the back (3).
Widespread throughout Europe from northern Spain to Scandinavia, reaching as far east as Russia. Once widespread throughout much of Britain, the pearl-bordered fritillary has suffered a severe and rapid decline in England and Wales over last 50 years (2). It has become locally extinct in most of Wales, and central and eastern England (4).
Found in woodland clearings, open deciduous wood pasture in Scotland, and in free-draining areas with a patchwork of grass, bracken and some scrub. The pearl-bordered fritillary requires abundant supplies of the main foodplants, common dog-violet (Viola riviniana) (4) and other Viola species (3) for the caterpillars, and plenty of nectar-rich spring flowers for the adults to feed on (5).
One of the first fritillaries to emerge, the flight period lasts for about six weeks and occurs between the end of April and late July. A single brood is usually produced; eggs are laid singly on dead bracken or leaf litter near the foodplant (4). The caterpillars emerge after about two weeks (3) and when they are still small (5) they hibernate amongst leaf litter and emerge the following spring to complete their development. They pupate in the leaf litter and adults emerge after a few weeks (4).
In Britain, The pearl-bordered fritillary is currently one of the most rapidly declining butterflies. The main reason for the decline seems to be inappropriate habitat management, particularly the decline in woodland coppicing and loss of open areas and broad rides. In the last 20 years there has been a high level of local extinctions, this is thought to be due to the maturation of forestry plantations created in the 1950s and 60s, which have now become too dense for this species (4). Loss of suitable bracken habitat has also occurred, either because of bracken removal or overgrowth and scrub invasion (4). Grazing by livestock and the trampling that accompanies it, can help to maintain suitable habitat (2).
In key areas, appropriate grazing should be maintained and encouraged through agri-environment schemes. In a number of nature reserves supporting the pearl-bordered fritillary, traditional coppice management has been reinstated with promising results. However many large populations are at risk in Scotland due to the practice of fencing off woodland and promoting natural regeneration, which although beneficial for some species, will result in a loss of edge habitat and clearings needed by this and other species of butterfly (4). The pearl-bordered fritillary is a priority species under the UK Biodiversity Action Plan (2).
For more information on the pearl-bordered fritillary see:
- Butterfly Conservation:
- Butterfly Conservation's Species Action Plan:
- Asher, J., Warren, M., Fox, R., Harding, P., Jeffcoate, G., and Jeffcoate, S. (2001) The Millennium Atlas of Butterflies in Britain and Ireland. Oxford University Press, Oxford.
Information authenticated by Butterfly Conservation:
- Agri-environment schemes: these schemes allow the government to compensate farmers for using methods that benefit the environment. The two main initiatives in the UK are the Countryside Stewardship Scheme and Environmentally Sensitive Areas. Since October 2000 these have formed part of the England Rural Development Programme (EDRP), administered by DEFRA, the Department of Environment Food and Rural Affairs. For more on these initiatives see: <link>http://www.defra.gov.uk/erdp/erdphome.htm</link>
- Coppicing: traditional form of woodland management in which trees are cut close to the base of the trunk. Re-growth occurs in the form of many thin poles. Woodlands are cut in this way on rotation, producing a mosaic of different stages of re-growth.
- Deciduous: a plant that sheds its leaves at the end of the growing season.
- Hibernate: a winter survival strategy characteristic of some mammals in which an animal's metabolic rate slows down and a state of deep sleep is attained. Whilst hibernating, animals survive on stored reserves of fat that they have accumulated in summer. In insects, the correct term for hibernation is 'diapause', a temporary pause in development and growth. Any stage of the lifecycle (eggs, larvae, pupae or adults) may enter diapause, which is typically associated with winter.
- Pupate: the process of forming a pupa, the stage in an insect's development, when huge changes occur that reorganise the larval form into the adult form. In butterflies the pupa is also called a chrysalis.
- Rides: the footpaths and access tracks which run through and divide blocks of trees in woodland. Many rides contain a mixture of rich flora and structure, and provide different habitat conditions for a range of wildlife.
- Still, J. (1996) Collins Wild Guide: Butterflies and moths of Britain and Europe. HarperCollins Publishers, London.
UKBAP (March, 2002)
- Carter, D.J. and Hargreaves, B. (1986) A Field Guide to Caterpillars of Butterflies and Moths in Britain and Europe. Collins, London.
- Asher, J., Warren, M., Fox, R., Harding, P., Jeffcoate, G. and and Jeffcoate, S. (2001) The Millennium Atlas of Butterflies in Britain and Ireland. Oxford University Press, Oxford.
Barnett, L.K. and Warren, M.S. (1999) Species Action Plan, Pearl-bordered fritillary, Boloria euphrosyne. Butterfly Conservation, Wareham. Available at: